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In New Jersey Pines, Trouble Arrives on Six Legs

In Mays Landing, N.J., last month, Nick Bleyhl cut a pine tree whose yellow needles indicated infection by southern pine beetles. He was part of a crew working for the state forest service to curb the spread of the insect, now endemic.Credit
Richard Perry/The New York Times

BLUE ANCHOR, N.J. — “Heads up!”

Deep in the woods, the whine of chain saws pierced the fall air, and Steve Garcia shouted a warning to fellow loggers as a 40-foot pitch pine crashed to the ground.

He was chopping down trees to save the forest as part of New Jersey’s effort to beat back an invasion of beetles.

In an infestation that scientists say is almost certainly a consequence of global warming, the southern pine beetle is spreading through New Jersey’s famous Pinelands.

It tried to do so many times in the past, but bitterly cold winters would always kill it off. Now, scientists say, the winters are no longer cold enough. The tiny insect, firmly entrenched, has already killed tens of thousands of acres of pines, and it is marching northward.

Scientists say it is a striking example of the way seemingly small climatic changes are disturbing the balance of nature. They see these changes as a warning of the costly impact that is likely to come with continued high emissions of greenhouse gases.

The disturbances are also raising profound questions about how to respond. Old battles about whether to leave nature alone or to manage it are being rejoined as landscapes come under stress.

The New Jersey situation resembles, on a smaller scale, the outbreak of mountain pine beetles that has ravaged tens of millions of acres of forest across the Western United States and Canada. That devastation, too, has been attributed to global warming — specifically, the disappearance of the bitterly cold winter nights that once kept the beetles in check.

In contrast to the West, where dying evergreens are splayed across steep mountainsides for all to see, the invasion in New Jersey has received barely any notice. The state’s pine forests occupy relatively flat land, and the scope of the damage is obvious only from the air.

“It’s a tremendously serious issue, but it hasn’t gotten anybody’s attention,” said State Senator Bob Smith, a Democrat from Piscataway and the chairman of the Environment and Energy Committee.

Photo

A section of pine bark showing damage from a southern pine beetle infestation.Credit
Richard Perry/The New York Times

Scientists and foresters say the lack of public pressure has meant that the state has been slow to mount an adequate response. They are worried that the beetles will not only devastate the Pinelands, but will also eventually attack coastal pinelands on Long Island and Cape Cod.

In New Jersey, the beetles hit a peak in 2010, when they killed trees across 14,000 acres of state and private land. More recently, the damage has been a few thousand acres per year. But with the beetle now endemic in New Jersey, experts do not think that reprieve will last.

“I’m worried about when we really get a superstress on the trees,” said George L. Zimmermann, a forest ecologist at Richard Stockton College of New Jersey, in Galloway. “If the beetle takes off, you could be talking not tens of thousands of acres, but a hundred thousand or more.”

Historically, it was too cold for the beetles to live north of Delaware. In their native habitat in the South, they are always present at low levels, surviving by attacking diseased or weakened pine trees.

The beetles, no bigger than uncooked grains of rice, burrow through a tree’s bark and consume a layer of tissue that provides the tree with nutrients and water. As the evergreens starve to death, they take on the color of a broadleaf forest in autumn.

Healthy trees can fight off small numbers of beetles by exuding a sticky sap that pushes them out. But a large beetle outbreak can overwhelm even vigorous trees. “The way they kill trees is the way wolves kill a moose — they do it by numbers,” said Matthew P. Ayres, a Dartmouth biologist who studies the beetles.

New Jersey has warmed by about 2.3 degrees Fahrenheit over the past century, but that average obscures the change that really matters.

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Winter nights of about 8 degrees below zero are needed to kill most beetles. The New Jersey climatologist’s office calculates that such bitter nights used to happen several times per decade in the state. But the last night that cold in the Pinelands was in 1996, and the beetle outbreak was first noticed five years later.

Dr. Ayres, one of the nation’s top beetle experts, has studied New Jersey closely for several years and has published research saying the rising temperatures have made the invasion possible. “I think the scientific inference is about as good as it gets,” Dr. Ayres said. “This is a big deal, and it’s going to forever change the way forests have to be managed in New Jersey.” The region of southern New Jersey once called the Pine Barrens — a term that has fallen out of favor — is the largest remnant of a once-vast coastal pine ecosystem stretching along much of the Atlantic Seaboard. It is partially protected by state and federal law, with about 300,000 acres owned by the public.

On a recent tour, Robert R. Williams, one of New Jersey’s most experienced private forest consultants, pointed time after time to dense stands of woods, thick with spindly pine trees and impenetrable underbrush — usually on state land.

Photo

An aerial view of Union Lake in Millville, N.J. The yellowing trees show the extent of the damage done by southern pine beetles.Credit
James Dunn/State Forestry Services

Long ago, fires would have helped keep the forest more open, but they have been suppressed across much of the country for a century to protect life and property. That has left many forests in an overgrown, unnatural condition.

Experience in the South has shown that such “overstocked stands,” as foresters call them, are especially vulnerable to beetle attack because the trees are too stressed fighting one another for light, water and nutrients. Control of the pine beetle has been achieved there by thinning the woods, leaving the remaining trees stronger.

Mr. Williams, who is critical of New Jersey’s government, advocates a similar approach, involving controlled burns and selective tree-cutting. Mr. Smith, whose college degrees include one in environmental science, pushed through a bill that would have encouraged the state to manage its forests more aggressively. But several environmental groups were suspicious that large-scale logging would ensue.

“We saw this legislation as an excuse to come in under the guise of ‘stewardship’ to open up our forests for commercial operations,” said Jeff Tittel, the director of the state’s Sierra Club chapter.

To allay such fears, the senator included a requirement that any state forest plan receive certification from an outside body, the Forest Stewardship Council, which is trusted by many environmental groups.

That approach has been followed successfully in other states, including Maryland. But Gov. Chris Christie vetoed the bill, saying he could not allow the state to “abdicate its responsibility to serve as the state’s environmental steward to a named third party.”

Larry Ragonese, a spokesman for New Jersey’s Department of Environmental Protection, said the state was working on a “new, comprehensive forestry management plan.” Right now, the state is essentially spot-treating beetle outbreaks in hopes of slowing the infestation.

State workers are searching from the air for the telltale red that signals dying pines.

Recently, off Piney Hollow Road in the Winslow Wildlife Management Area, three part-time loggers, including Mr. Garcia, revved their chain saws as they chopped down nearly an acre of pines on state land. Because most beetles do not fly far from the tree where they hatch, cutting out diseased trees can slow their spread.

Lynn E. Fleming, New Jersey’s state forester, said she hoped to confine the beetles to the southernmost part of the state, south of the Mullica River, keeping them out of the heart of the Pinelands. But the beetles are not cooperating; they keep jumping the river.

Dr. Ayres said that if climatic warming continues, nothing would stop them from eventually heading up the coast. That means forest management is likely to become critical in many places where it has been neglected for decades.

“It’s hard for some people to accept — ‘What, you have to cut down trees to save the forest?’ ” Dr. Ayres said. “Yes, that’s exactly right. The alternative is losing the forest for saving the trees.”

A version of this article appears in print on December 2, 2013, on Page A1 of the New York edition with the headline: In New Jersey Pines, Trouble Arrives on Six Legs. Order Reprints|Today's Paper|Subscribe